Lipase catalyzed synthesis of oligomeric diol building blocks utilizing sophorolipid-derived hydroxy fatty acids

• Main Authors: Zerhusen, Christian, Chavez Linares, Pilar, Sonnabend, Maresa, Leimenstoll, Marc C., Schörken, Ulrich
• Format: Book Part
• Language: English
• Published: 2019
• Subjects: ddc:500; Antarc*; Antarctica
• Online Access: https://epb.bibl.th-koeln.de/frontdoor/index/index/docId/1412; https://nbn-resolving.org/urn:nbn:de:hbz:832-epub4-14125; https://epb.bibl.th-koeln.de/files/1412/Zerhusen_STEPsCON_2018_Proceedings.pdf

The synthesis of 17-hydroxy-oleic acid based oligomeric esters was investigated with immobilized Pseudozyma antarctica Lipase B and hexanediol as co-substrate. The effects of different reaction parameters on velocity and product composition at equilibrium conditions were analyzed. The synthesis of oleic acid esters was used as a reference system for initial evaluation of reaction parameters. The reaction with oleic acid and hexanediol was fastest at an enzyme concentration of 5% at 60 °C and high conversions of > 90 % were achieved in non-polar solvents in the presence of molecular sieves. In heptane an oleic acid conversion of 96 % was reached with a final diester to monoester ratio of > 4:1. In syntheses trials with 17-hydroxy-oleic acid the formation of oligomers was verified with GPC, however; conversion was generally lower than with oleic acid. Removal of hydroxyl fatty acid monomers and dimers and the formation ester functionalities could be verified by GC analysis. An increase of the degree of oligomerization was observed simultaneously by GPC analysis. The number-average molecular weight was around 1400 in the best trials corresponding to a degree of oligomerization of around 4 units of hydroxyl-fatty acid attached to a hexanediol core. Though transformations were not complete, the final oligomer size was in the lower range of polyester diols used for polyurethane manufacturing.